1. Field of the Invention
The present invention relates to a lens-fitted photo film unit with a flash device. More particularly, the present invention relates to a lens-fitted photo film unit with a flash device and changeable in plural photographing modes one of which is suitable for daylight synchronized flash photography.
2. Description Related to the Prior Art
A lens-fitted photo film unit is widely used, which is preloaded with unexposed photo film. It enables a user to take photographs easily. When he or she forwards the lens-fitted photo film unit to a photo laboratory after exposing all frames in a photo film, prints produced from the photo film are supplied to him or her. Also, the processed photo film is returned together.
There is a type of the lens-fitted photo film unit in which an electronic flash device is incorporated for photographing an indoor or night scene. JP-A 09-015693 discloses the lens-fitted photo film unit in which an aperture stop changer mechanism is actuated in response to operation of a charger switch charging the flash device, for changing a diameter of an aperture stop for a photographic optical system with a taking lens.
The lens-fitted photo film unit according to this prior document has a mechanism for increasing the diameter of the aperture stop at the time of an exposure with flash light, namely for setting a decreased value of f-number for the aperture stop. This is effective in photographing an object including a background in an indoor or night scene with insufficient illumination.
In the field of photography, daylight synchronized flash photography is known, in which an exposure is taken with the flash light even under daylight in a sunny weather. The daylight synchronized flash photography is typically effective in a rear light scene, because the flash light can illuminate a principal object and prevents it from being too dark.
If an exposure is taken by daylight synchronized flash photography with the lens-fitted photo film unit according to the above prior document, the aperture stop has the greater diameter even under daylight, to cause an excess in the exposure amount. Overexposed frames causes the negative photo film to increase time required for producing prints from the photo film in the photo laboratory. Efficiency in the printing in the photo laboratory is lowered, so that printing cost per frame is raised. Also, a decrease occurs in the printing quality.
In view of the foregoing problems, an object of the present invention is to provide a lens-fitted photo film unit with a flash device and capable of photographing an indoor or night scene appropriately and photographing a daylight scene in daylight synchronized flash successfully.
In order to achieve the above and other objects and advantages of this invention, a lens-fitted photo film unit includes a main body pre-loaded with photo film. A flash unit is secured to the main body, for emitting flash light to a photographic field. An exposure opening is formed in the main body, for introducing light from the photographic field to the photo film. A shutter mechanism is secured to the main body, actuated in synchronism with the flash unit, for opening and closing the exposure opening. A charger switch causes the flash unit to store charge upon being turned on. An aperture stop changer is shiftable to first and second set positions, for stopping down the exposure opening when in the first set position. A linking mechanism allows turning on and off the charger switch when the aperture stop changer is in the first set position, and forcibly turns on the charger switch when the aperture stop changer is in the second set position.
The aperture stop changer includes a changeover plate movable to the first and second set positions. A small diameter opening is formed in the changeover plate, has a diameter smaller than a diameter of the exposure opening, is set at the exposure opening when the changeover plate is in the first set position, and set away from the exposure opening when the changeover plate is in the second set position.
Furthermore, a charger member turns on the charger switch upon being operated externally. The changeover plate is disposed to extend between the exposure opening and the charger switch. The linking mechanism includes a first end of the changeover plate, and the first end is away from between the charger switch and the charger member when in the first set position, and is behind the charger member when in the second set position to press a front of the charger switch.
Furthermore, an operation projection is formed to project from the changeover plate, operable externally, for moving the changeover plate to the first and second set positions.
Furthermore according to a preferred embodiment, a charger button portion is formed with the changeover plate, extended from a front face of a first end thereof closer to the charger switch, deformable with resiliency, for turning on the charger switch upon being depressed externally.
The linking mechanism includes a rear face of the first end, the rear face is away from a front face of the charger switch when the changeover plate is in the first set position, and pushes the front face of the charger switch when the changeover plate is in the second set position.
The linking mechanism further includes a projection for projecting from the rear face of the first end.
Furthermore, a front cover covers a front of the main body. An access opening is formed in the front cover, and disposed in front of the charger button portion. An operation projection is formed to project from the charger button portion, operated externally through the access opening, for sliding of the changeover plate and for depression of the charger button portion.
Furthermore according to another preferred embodiment, a large diameter opening is formed in the changeover plate, has a diameter larger than the diameter of the small diameter opening, and is set at the exposure opening when the changeover plate is in the second set position.
The large diameter opening comprises an arc-shaped recess formed in one end of the changeover plate.
The photo film has speed from ISO 800 to ISO 3200, the exposure opening has an f-number from f/5.6 to f/8, and the small diameter opening has an f-number from f/13 to f/27.
Furthermore according to still another preferred embodiment, a charger member is movable to first, second and third mode positions, wherein the charger member, when in the first mode position, turns off the charger switch, and when in the second mode position, turns on the charger switch and causes the linking mechanism to move the changeover plate to the first set position, and when in the third mode position, causes the linking mechanism to move the changeover plate to the second set position.
The linking mechanism includes an end portion of the changeover plate. A spring biases the changeover plate to the first set position. A driving projection is formed to project from the charger member, disposed close to the end portion, wherein the driving projection, when the charger member is in the first and second mode positions, is moved away from the end portion, and when the charger member is in the third mode position, presses the end portion to move the changeover plate to the second set position.
The changeover plate is pivotally movable.
The flash unit has a circuit board. The charger switch includes first and second contact points disposed in a front of the circuit board. The charger member includes a contact segment for being away from at least one of the first and second contact points when in the first mode position, and for contacting the first and second contact points simultaneously when in the second and third mode positions.
The second mode position is disposed between the first and third mode positions.
The charger member is slidable to the first, second and third positions.
According to another aspect of the invention, a charger switch causes the flash unit to store charge upon being turned on. An aperture stop changer is shiftable to first and second set positions, for stopping down the exposure opening when in the first set position. A charger member is movable to first, second and third mode positions upon being operated externally, for turning off the charger switch when in the first mode position, and for turning on the charger switch when in the second and third mode positions. A linking mechanism shifts the aperture stop changer to the first set position when the charger member is in the first and second mode positions, and shifts the aperture stop changer to the second set position when the charger member is in the third mode positions.